1. Field of the Invention
The present invention generally relates to thermally decomposable organometallic source reagents that are useful for the formation of metal films on substrates. More specifically, the invention relates to nitrogen analogs of Copper II xcex2-diketonates as source reagents useful in semiconductor processing for deposition of films comprising copper.
2. Description of the Related Art
Thermal decomposition of organometallic source reagents is a particularly attractive method for forming metal films because it is readily scaled up to production runs and because the electronics industry has a wide experience and an established equipment base in the use of vaporization and decomposition technology.
Semiconductor processing requires source reagents that are sufficiently volatile to permit their gas phase transport into the decomposition reactor. The source reagent must decompose in the reactor to deposit only the desired element(s) at the desired growth temperature on the substrate. Premature gas phase reactions are desirably avoided, and it generally is desired to controllably deliver source reagents into the reactor to effect correspondingly close control of film stoichiometry.
Many potentially useful metal compounds are not well suited for semiconductor processing. For example, some potential source reagents are solids that are amenable to sublimation for gas-phase transport into the reactor, however the sublimation temperature may be very close to the decomposition temperature. Accordingly, the reagent may begin to decompose in the lines leading to the reactor, and it then becomes difficult to control the stoichiometry of the deposited films.
Solvents such as tetrahydrofuran or diethyl ether or excess ligands may enhance vaporization of source reagents by forming a complex. However, release of the solvents or excess ligands during semiconductor processing can result in unpredictable variations in processing conditions.
Accordingly, there is a continuing search in the art for improved source reagent compositions which are more amenable to vaporization to form the source component vapor for semiconductor processes.
The present invention provides nitrogen containing analogs of Copper II xcex2-diketonates which analogs are stable source reagents for copper deposition when separated from solvents and excess ligands. The nitrogen containing analogs replace xe2x80x94Oxe2x80x94 with xe2x80x94N(Rxe2x80x3)xe2x80x94 wherein Rxe2x80x3 is an alkyl group having from one to four carbon atoms. Replacement of each xe2x80x94Oxe2x80x94 is preferred although replacement of one xe2x80x94Oxe2x80x94 per cyclic ring is sufficient to improve stability of the copper source reagents. The nitrogen containing analogs can be separated from solvents and excess ligands by sublimation.